In 1909, Petrosino was sent to Italy to infiltrate the Sicilian Mafia and uncover the roots of the Black Hand gangsters that had immigrated to the United States.

But the mob got a tip about Petrosino’s true identity and had ordered him killed. Petrosino received a message to meet an informant in the city’s Piazza Marina. While waiting for his source, he was gunned down by assassins.

Many experts believe, Casioferro, who had become a powerful Sicilian leader, was behind the killing.

More than 250,000 people attended his New York funeral. Some of his crime-fighting techniques are still practiced today.